Your back is a gateway to the sky.
The celestial dance,
The story of space and time,
is coded in the spine.
To the area around your tailbone,
Vibrating with luminous space,
And to the spine as a channel
Gushing with radiant emptiness.
Where particles flash in and out of existence,
Is the origin of the mind.
(~ from the Radiance Sutras by Lorin Roche, PhD - originally known as the Vijanana Bhairva Tantra, an ancient tantra text)